Gear shift damper



Se t. 7,1937, 0. K. KELLEY GEAR SHIFT DAMPER Filed NOV. 16, 1935 2 Sheets-Sheet l se u, 1937; O. K ;KELLEY ,0 ,58

GEAR SHIFT DAMPER Filed Nov. 16, 1955 2 Sheets-Sheet 2 4m fellgz Patented Sept. 7, 1937 UNITED STATES can smr'r paurna Oliver K. Kelley, Pontiac, Mlcln. assignon'by mesne assignments, to

Yellow Truck and Coach Manufacturing Company, Pontiac, Mich a corporation of Maine Application November 10; ms: Serial No. 50,149

r (oi. lea- 31) This inventionrelates to power opera ted sys-- 'tems for shifting change speed gearing of motor 'vehicles and the like. Itconcerns particularly transmissions of the synchromesh type and the movement of the parts into drive transmitting relation. "Transmissions-of this sort have synchronizing clutches associated with the toothed driving elementsto be meshed and in the operation of engaging driving and driven elements the .initial movement of the shifter device brings the frictionalclutchinto action to equalize relative speed and permit the coupling teeth to slide smoothly into mesh during the continuing and. final movement of the shifter device.

In-passenger coach or bus installations wherein the power plant is located at the rear of-thevehicle or otherwise removed from the forward station of the operator, attempts have been made to shift gears by a power system wherein air under pressure is fed under control of a master valve within convenient reachof the operator-to one or more pressure responsive devices opera- ,tively connected with the shifter mechanism in the gear box. Satisfactory results have not been had because with the initial action of the pressure responsive device the synchronizing friction clutch engages and" this increases resistance to further movement of the shifter mechanism whereby pressure builds up inthe'pressure responsive devic'e to an extent that after synchronizing is complete the gear elements are clashed or brought together finally with unnecessarily ,great force andspeed, which not only is likely to harm the parts but also produces objectionable noise. t I

In order to eliminate thedifilculty mentioned it is :here proposed to incorporate in a power shift system, preferably in association with the pressure responsive device, some means to compensate for pressure rise incident to the continuing fiow of pressure fluid duringthe synchro-- nization period and thereby insure smooth and quiet engagement, and particularly guard against sudden action after'synchronizatlon. The rate of I response inthe final movement may be consider ably retarded as may be desired, but in any event mesa of the shifter mechanism may 'be'jhad by proper choice and control of. resistance values in 5 relation to selected air pressure. a

For a better understanding of the invention referencemay be had to the accompanying draw ings, wherein Figure l is a longitudinal sectional, view shcwingga fragment of a changespeed sear mechanism for motor vehicles-with my improved shifter mechanism-applied thereto, and Figures 2 and 3 are'detail sectional views illustrating modifications. w v

Only so much of the complete power drive system is shown. in the drawings'asis necessary to 5 illustrate the invention. Theinvention may be applied to any conventional change speed gearing with speed synchronizing devices, an example of which is contained in Tenney Patent No.

In the drawings the numeral I indicates a gearbox or housing intd'yvhich project the input and output shafts 2 and 3.; respectively. Adapted to be'coupled individually with the output shaft 1 3 are the second speed andhig'h or direct speed is driving elements land 5, respectively, and which form part of a constant me'shgear train;v but the companion gears of the sets to be mounted on a countershaft are omitted in the drawings for the sake of simplicity. Thegeari for driving 20 3 the countershaft is mounted on'the end of the drive shaft-2 and through an internal bearing 8 pilots the end-of the output shaft 3. A cylinj drical extension I of the gears-5 has internally thereof a series of coupling teethand in axially 25 spaced relation thereto are similar coupling teeth on a tubular extension 8 of the second speed gear 4 which is mounted forrotation by the bearings 9 on the output shaft. Between the two sets of.

coupling teeth is 'a'slider collar l0 provided'at 3o 7 opposite ends with clutch teeth adapted for indl-- vidual engagement with the internal teeth on the" extensions I and 8, respectively. This slider collar II is splined' or keyed-to a spacer sleeveii I fixed on the-output shaft for rotationinunison withthe shaft. Thus movement of the collar it! toward the left in Figure lclutches the input and output shafts in direct driving relation while movement of the slider toward the right couples y the output shaft with the input shaft through the 40 constant mesh gear train.

Inasmuch as the coupling under normal conditions is effected while the vehicle is in motion and the engine clutch disengaged, thetspeed of I rotation of the output shaft and, therefore, the

; slider it, will difler from thatof either of the va different rate for the initial and final movegear'elements l and 5, and to insure an easy mesh 'ing of the teeth in-the shifting operation the common practiceis toflrst frictionally clutch. the

' slider and the gear element tobe engaged. To

effect suchsynchronization of spe d the slider Iii v is provided with a sleeve "having conical clutch siu'faces' at opposite ends for frictional contact I2 is provided 'on the periphery thereof and a cooperating internal tapered surface is formed on a ring l3 carried by the'gear element 4. A bearing ring I4 is riveted or otherwise secured interlorly of the sleeve for sliding engagement with the cylindrical extension 8. n the other end of the sleeve an internal ring l5 provides a friction clutch surface for engagement with the tapered peripheral surface on the extension I of the gear I. One or more spring pressed poppets I serve to locate the sleeve l2 with reference to theslider l0 and the slider likewise is provided with a number of radial projections I! which are movable through axially elongated slots IS in .the sleeve l2 and are connected by studs or pins I! with a ring 20 surrounding the sleeve l2 and having an annular groove to receive a shifter fork. By means of synchronizing cones provided head 28 fixed to a shift rail 21 which is mounted in suitable bearings in the cover 23 of the gear box. As is well understood, the usual 'gear box involves two or more shift rails, depending upon the number of gear trains involved and the heads of the several forks are each provided with slots as at 29 which in the neutral position of the parts are in transverse .aiinement with each other for the movement therethrough of a selector foot 30 mounted on a rockable and shiftable rail 3|. when the rail 3| is rocked the selector arm 30 forks to slide the same in unison therewith upon the subsequent shifting movement of the rail 3|. To rock the rail back and forth there may be provided as a part of the power shifter system a pressure responsive device, not shown, arranged as described in my pending application for patent Serial No. 34,339, filed August 2, 1935.

For shifting the rail 3| after a selection has been made, a pressure responsive device is provided in the form of a hollow cylinder 32 fastened on the end of the cover 23 and enclosing a slidable piston 33 mounted on the rail 3| and which rail extends through the cylinder 32 with suitable packings 33 in the. opposite walls thereof.

Air or other fluid under pressureislntroduced into the cylinder 32 on one side of the piston through a conduit 35 and to the opposite side of the piston through a conduit 33 both leading from the source of supply and being under control of the operator by suitable valving. A secondary pressure cylinder 31 of smaller diameter than the main cylinder 32 encloses a piston -38fon the end of the shift'rod 3|. For convenience and economy of manufacture the two cylinders may be formed as a single casting in which event the end wall 38 of the cylinder 31 will be formed as a removable plate,to facilitate assembly. The space within the two cylinders on adjacent sides of the two pistons areinterc onnected with each other as by means of an exterior conduit 40 and suitable pipe fittings which extend between apertured bosses integral with the cylinder casting. In the case of the boss associated with the'main cylinder the communication is by means of a small diagonal passageway 3| which is closedby the piston 33 in its intermediate or neutral position. A similar port 42 arranged in axially .spaced relation to the port ll is intended to. communicate through a conduit 43 the spaces within the two cylinders on the remote sides of the respective pistons, and this port is also closed by the piston 33 in the intermediate or neutral position of the parts.

Assuming the selector arm 30 to be engaged with the head 29 and the parts in the position illustrated in the drawings, the output shaft 3 may be coupled with the second speed gear upon the movement of the shifter rod. 3| toward the right through the introduction of air under pressure through the conduit 35. The air under pressure acting against the piston 33 moves the piston a small amount until the synchronizingcones come into engagement. This movement is not enough to uncover port 42, and momentarily further movement is now resisted while synchronizing takes place, but in this momentary lag of the piston, pressure within the left end of cylinder 32 builds up to. an appreciable degree.

After synchronizing has been completed and the piston has resumed its motion the port 32 is immediately uncovered to relieve pressure by allowing air to flow into the secondary cylinder through the conduit 43. Thereafter the smaller piston acts inopposition to the larger piston and further movement is at a somewhat reduced rate inasmuch as the effective area acted on by the pressure is the difference in surface areas. between the two pistons. The action is the same when a shift into third speed position is to be effected with the air under pressure supplied through the conduit 36 acting first on the large piston 33 and finally on the two pistons in opposition to each other whereby the coupling of the toothed clutching elements is effected smoothly after synchronization has been effected. moves into engagement with one of the shift 5 the piston 53 in the neutral and synchronizing positions of the parts, at which time there is also closed the axially spaced port 54 communicating through the line 55 with the expansion chamber 56. In this case, air under pressure introduced into the piston cylinder 51 through the pressure supply line 58 moves the piston toward the right to first synchronize speed and then complete the shift with the port 52 being uncovered after the synchronizing movement of the piston so that the pressure is relieved for the final movement. Likewise movement of the piston in the opposite direction under pressure of air supplied through the conduit 59 uncovers the port it after a predetermined extent of movement for communicating the expansion tank 56 with the piston cyliner. Mechanical means for retarding the rate of movement may be constructed as shown in Figure 3. In this case the piston cylinder 30 has an extension 6| provided with end walls 62 and 63 and through which extension projects a reduced portion 64 of the piston rod 65. At its end the reduced shaft portion carries a nut 33 or.

other suitable shoulder for engagement with a plate or washer 31 .slidable on the shaft and a somewhat similar. plate or washer 33 alsoslidable on'the shaft is adapted to be seated on the aoeasso shoulder 69 on the shaft n. 'In the neutral position 01' the'piston 10 the plate 61 is seated both on interposed a coil spring II which oiIers resistanceto piston movement in both directions inasmuch as the plates 61 and 68 are moved toward each other in either event. Also enclosed within the extension 6| is a larger spring 12 which seats at opposite ends against washers l3 and Il adapted to bear against the end walls 62 and 63. Each washer is provided with an inwardly extending offset 15 arranged in spaced relation with the plates 61 and 68 so that after the synchronizing movement of the piston but before engagement of the drive gear clutches one or the other of the washers II-ll will be picked up and further movement will be against thecombined forces ofthe springs Ii and 12. Thus there will be eliminated the suddenness ot final movement of the shifter mechanism in coupling the drive gear clutches.

I claim:

1. The combination with a pairof relatively movable drive transmitting members having speed synchronizing mechanism, means operative first to bring said synchronizing mechanism into action and then effect a drive relation of the members, of a fluid pressure device for operating said means, and cushioning means effective after movement of the member, to slow down the rate of final movement under the continued application of power. 1

3. For use with change speed gearing having synchronizing mechanism associated therewith. fluid pressure actuated gear changing means including a pair of pressure responsive devices coupled together for action in opposition, means eiIecting the application of fluid pressure to one of said devices and other means controlled by the response 0! the last mentioned device i'or diverting the application of fluid pressuretherefrom I to the other of said devices.

4. For use with change speed gearing having speed synchronizing mechanism associated therewith, fluid pressure actuated gear changing means including a fluid pressure responsive device, means to supply fluid under pressure thereto at a uniform rate and elastic motion resisting means of two stages cooperating with said pressure responsive device and being constructed and arranged to have one stage ineiIective during the initial response of said device.

5. In combination with change speed gearing having speed synchronizing mechanism, of a fluid pressure gear changing system including, a primary piston and cylinder, a secondary piston and cylinder having an eiIective surface area differing from that of the primary piston. and cylinder, a connection between said pistons for their unisonal movement, means supplying fluid under pressure to the primary cylinder and a communicating conduit between said cylinders controlled by the position of the primary piston to open or close said conduit for the flow of fluid under pressure from the primary cylinder to the secondary cylinder for action on the secondary piston.

6. In combination with change speed gearing having speed synchronizing mechanism, of a fluid pressure gear changing system including a pair of diflerential size pistons arranged in tandem, pressure cylinders enclosing said pistons for movement in unison, means for introducing fluid under pressure to one oi! the cylinders to move the piston therein and means communicating said cylinders after a given movement of said piston for introducing fluid pressure into the other cylinder for action on the piston therein to retard the rate of piston travel.

7. In a construction of the character described, driving and driven elements adapted to be coupled, speed synchronizing mechanism therefor, a member movable to bring the synchronizing mechanism into action and then couple said driving and driven elements upon further movement,- a fluid pressure responsive device including a pressure chamber connected with the member to move the same, an expansion chamber and means to connect the expansion chamber with the-pres sure responsive device whereby said expansion chamber will be placed in communication with mechanism comes into action for retarding the rate of movement in the coupling of said elements. I

OLIVER. K. KELLEY.

I said pressure chamber after the synchronizing 

